1,1,1,2,3,3,3─七氟丙烷的气相声速

分析了气相声速与理想气体比定压热容的热力学关系,用超声变程干涉仪测定了１,１,１,２,３,３,３－七氟丙烷（ＨＦＣ－２２７ｅａ）的 ７２组气相声速值,温度范围 ２７３－３３３ Ｋ,压力范围 ２６－３１５ ｋＰａ,测量不确定度小于 ０．０５％。根据这些实验数据,确定了ＨＦＣ－２２７ｅａ的理想气体比定压热容和声速第二维里系数,并分别拟合得到了与温度的函数,理想气体比定压热容的不确定度小于 ０．５％．使用方阱势能模型导出了 ＨＦＣ－２２７ｅａ的第二维里系数,并与文献值进行了比较。     

1,1,1,2,3,3,3- 七氟丙烷的气相声速

析了气相声速与理想气体比定压热容的热力学关系,用超声变程干涉仪测定了1,1,1,2,3,3,3-七氟丙烷(HFC-227ea)的72组气相声速值,温度范围273-333 K,压力范围26-315 kPa,测量不确定度小于0.05%。根据这些实验数据,确定了HFC-227ea的理想气体比定压热容和声速第二维里系数,并分别拟合得到了与温度的函数,理想气体比定压热容的不确定度小于0.5%。使用方阱势能模型导出了HFC-227ea的第二维里系数,并与文献值进行了比较。     

HFC-227ea的维里系数研究

ＨＦＣ－２２７ｅａ是一种有希望的新环保制冷剂,特别是作为混合物中的一种组元用于Ｒ２２和Ｒ５０２的替代,但其热物性数据十分有限。本文使用膨胀定容法高精度地测量了ＨＦＣ－２２７ｅａ的气相ＰＶＴ性质,沿定温线外推确定了其第二和第三维里系数,并与文献值进行了比较;使用截断维里方程,根据本文所确定的维里系数,可以高精度地再现ＨＦＣ－２２７ｅａ的气相区热力性质。     

干涉法测量气体低压下声速的实验研究

介绍了干涉法测量气体声速的试验原理和变程干涉声速测量的实验系统,使用本套测量系统测得的气体声速的精度可达5×10-4。根据热力学原理,分析了气体声速与理想气体比定压热容之间的物理关系。在本套实验系统上测得了一批高精度的新环保制冷剂的气相声速数据,并可进一步确定其理想气体比定压热容.     

HFC—32的热力学性质

1前言HFC－32和其它HFC类物质的混合物被认为是HCFC－22的最有希望的替代物，因此，需要HFC－32的热物理性质。本文提供了一个适用于整个区域的HFC－32状态方程，结合理想气体比热关系式，给出了HFC－32各种热力性质，如：PVT（压力-比容-温度），内能，Helmholtz函数，Gibbs函数，焓，熵，等容比热，等压比热，声速等的计算式。另外，还给出了单独的饱和蒸气压和饱和液密度关联式。2蒸气压方程与饱和液密度方程至今已有多位学者测量过HFC－32的饱和蒸气压，提供了从180K至临界温度的蒸气压测量数据，根据实验中使用的样品纯度…     

饱和态下制冷工质的新状态方程

饱和态下制冷工质的新状态方程李斯特，高武子，靳包平（北京化工学院机械系北京１０００２９）关键词：饱和态，制冷工质，维里系数一、引言本文根据统计力学原理，结合本课题组曾提出的实际气体和液体的数学模型，经推导建立了一则适合饱和态下制冷工质的新状态方程；同...     

应用扩展的2CJL模型确定微观势能参数

本文应用扩展的2CLJ势能模型优化了若干线型分子的微观势能参数.该模型包含了二分子间长程静电和诱导作用,同时也考虑了极性分子偶极矩与分子轴不平行的情况.通过第二维里系数的实验数据回归获得简单线型分子N2、O2、Cl2、F2、CO、NO、C2H6和C2F6的硬球直径σ和阱深ε.强极性分子CH3Cl、CH3F、CH3CF3、CF3CH2F和CH3CHF2的第二维里系数运用改进的混合规则计算得到,计算结果与实验数据符合很好.     

HFC-32饱和气导热系数的实验研究

1研究背景自《蒙特利尔议定书》签定后，特别是1992年11月哥本哈根会议以来，HCFCS的替代日程已经确定。目前以含有HFC－32的混合物替代HCFC－22的呼声很高，而且国外正开始着手应用。有关HFC－32的饱和气的导热系数现在还没有见文献报导。在本文中，作者自行开发设计了一套双热线法测量导热系数的实验装置，并对HFC－32的饱和气的导热系数进行了测量，经分析测量结果是令人满意的。2实验装置及实验原理热线法是测量导热系数的瞬态方法之一，其基本原理是Carslaw提出的半径趋于零的无限长线热源在无限大介质中的导热方程的解山文献…     

线型分子势能函数及第二维里系数计算

本文以两中心的Lennard—Jones（2CLJ）流体为研究对象,通过引入与温度相关的势能参数,提出了改进型的2CLJDQP势能函数模型。应用此模型计算了乙烷（C2H6）、六氟乙烷（C2F6）、氟甲烷（CH3F）、氯甲烷（CH3C1）、1,1,1-三氟乙烷（CH3CF3）、二氟乙烷（CH3CHF2）的第二维里系数,较...     

丙烷气相音速与理想气体比热的实验研究

用球共鸣声学法测量了工质丙烷（Ｒ２９０）在温度分别为２９３．４８ Ｋ、３０２．９６Ｋ、３１３．２１Ｋ和３２３．１９Ｋ时,压力从２００ｋＰａ～７００ｋＰａ范围内的四条等温线共２８个音速数据。温度、压力和气体音速测量的不确定度分别为±１４ｍＫ、２．０ｋＰａ和±０．００３７％．根据实验数据,由热力学关系式得到了Ｒ２９０在四个温度下的理想气体比热和第二音速维里系数．同时根据现有的高精度实验数据拟合Ｒ２９０的理想气体比热方程．这些研究为Ｒ２９０在工程上的应用提供了必需的热物理性质基础数据．     

Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide

Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs.     

Hybrid Wavelength and Code Division Multiple Access in Optical Networks

A review of schemes for multiple access in fiber optic networks shows that a hybrid of wavelength and code division multiple access (WCDMA) combines the best features of both. In particular, the hybrid scheme retains the large information carrying capacity of wavelength division multiple access (WDMA) and flexibility of code division multiple access (CDMA). In this paper WDMA, optical CDMA (OCDMA), and WCDMA networks are discussed. In OCDMA networks, concept of incoherent and coherent coding including inverse decoding and matched filter is introduced. The delay performance of both WDMA and WCDMA networks, under the simple suboptimum access protocols based on cyclic search, is computed. It has been shown quantitatively that tuning delay significantly affects the delay performance of both WDMA and WCDMA networks. Futhermore, delay performance of WCDMA networks is always better than the WDMA networks for the same tuning delay, load, and number of users.     

Effect ofγ-radiation on the spectral luminescence characteristics of impure cadmium tungstate crystals

Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation (5.5·10⁴ Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure crystals is analyzed (preliminarily). Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997.     

Femtosecond Transform-Limited Pulse Generation by Compensating for the Linear Chirp of SPM Spectra in Dispersion Shifted Fibers

A simple technique of pulse compression, based on the linear chirp compensation of self-phase modulation (SPM) spectra in dispersion shifted fibers, is demonstrated. The optimization procedure is carried out, for a short span of a single-mode fiber, using a parabolic law, which describes the behavior of the squared output pulse width versus the pump peak power in the case of Gaussian pulses. The experimental results give a minimum pulse duration of 233 fs, which is in good agreement with the model. Shorter and coherent pulses, down to 90 fs, have been obtained by inserting an interference filter at the optical output.     

Sorting of bending magnets for the SSRF booster

The Shanghai Synchrotron Radiation Facility(SSRF)booster ring,a full energy injector for the storage ring,is deigned to accelerate the electron beam energy from 150MeV to 3.5GeV that demands high extraction efficiency at the extraction energy with low beam loss rate when electrons are ramping.Closed orbit distortion(COD)caused by bending magnet field uniformity errors which affects the machine performance harmfully could be effectively reduced by bending magnet location sorting.Considering the affections of random errors in measurement,both ideal sorting and realistic sorting are studied based on measured bending magnet field uniformity errors and one reasonable combination of bending magnets which can reduce the horizontal COD by a factor of 5is given as the final installation sequence of the booster bending magnets in this paper.     

Measurement of nonlinear coefficient of optical fiber based on small chirped soliton transmission

We measure the waveform and phase curves of short optical pulses before and after transmission over different lengths of fibers by use of the pulse analyzer with the frequency-resolved optical gating (FROG),and numerically simulate pulse evolution under the experimental conditions.The nonlinear coefficient of the fiber is given by comparing the experimental results with the numerical ones.Difference between the experiment and numerical simulation is analyzed.     

Resonance scattering of canonical elastic shells in absorbing fluid medium

Resonance scattering of elastic spherical shell and cylindrical shell while the surrounding fluid medium has absorption is studied. The normal mode solution derived using exact elastic theory and the separation of variables is still applicable. However, the scattering form function has to be modified for the absorbing medium, otherwise the unreasonable result would be obtained. The backscattering form function in the absorbing medium is redefined, and the form function of elastic spherical and cylindrical shell with vacuum or solid matter filled is calculated in various absorption conditions. The results show that the absorption of surrounding fluid leads to notable attenuation of the coincidence resonances in the mid-frequency, but it has a little influence on the low-frequency resonance scattering induced by the filler inside the shell.     

Single-beam self-referenced phase-sensitive surface plasmon resonance sensor with high detection resolution

A versatile and low-cost single-beam self-referenced phase-sensitive surface plasmon resonance(SPR)sensing system with ultra-high resolution performance is presented.The system exhibits a root-mean-square phase fluctuation of ±0.0028.over a period of 45 min.i.e.a resolution of±5.2×10-9 refractive index units.The enhanced performance has been achieved through the incorporation of three design elements:a true single-beam configuration enabling complete self-referencing so that only the phase change associated with SPR gets detected,a differential measurement scheme to eliminate spurious signals not related to the sensor response,and the elimination of retardation drifts by incorporating temperature stabilization in the liquid crystal phase modulato .Our design should bring the detection sensitivity of non-labeling SPR biosensing closer to that achievable by conventional fluorescence-based techniques.     

Influences of SiO2 protective layers and annealing on the laser-induced damage threshold of Ta2O5 films

Ta2O5 films are prepared on BK7 substrates with conventional electron beam evaporation deposition.The effects of SiO2 protective layers and annealing on the laser-induced damage threshold (LIDT) of the films are investigated.The results show that SiO2 protective layers exert little influence on the electric field intensity(EFI)distribution,microstructure and microdefect density but increase the absorption slightly.Annealing iS effective on decreasing the microdefect density and the absorption of the films.Both SiO2 protective layers and annealing are beneficial to the damage resistance of the films and the latter is more effective to improve the LIDT.Moreover,the maximal LIDT of Ta2O5 films is achieved by the combination of SiO2 protective layers and annealing.